Samsung’s U.S. mobile executives debated using Google as a proxy to attack Apple in a marketing campaign because it felt constrained in going directly after the iPhone maker, a large customer of its components businesses.

Under the subject heading “Use Google to attack Apple?” Samsung executives exchanged emails a week before Apple’s introduction of the iPhone 4S in Oct. 2011. Apple introduced the emails as evidence to dispute Samsung’s claim that successful marketing and superior hardware helped drive its market share gains. The two companies are squaring off in U.S. district court in San Jose, Calif., in the latest round of their long-running patent feud.

The emails reflect a reality of the global technology landscape where the distinction between ally and enemy can change quickly. Apple is a major customer for Samsung’s chip and display businesses, but a bitter rival in smartphones. Google and Apple were once close with Google’s former CEO Eric Schmidt sitting on Apple’s board. But the two are now battling head to head for smartphone software dominance.

In a sign of their intensifying competition, Apple’s co-founder Steve Jobs declared that it needed to wage a “holy war” against Google in a separate email introduced earlier in the trial.

Michael Pennington, the former vice president of sales operations for Samsung’s U.S. mobile division, suggested that it should turn to Google in order to attack Apple because it can’t go after Apple directly:

As you have shared previously, we are unable to battle them directly in our marketing. If it continues to be Samsung’s position to avoid attacking Apple due to their status as a large customer, can we go to Google and ask them to launch a campaign against Apple, based on the many better Android options in the market for Q4.

He added:

Seems Google should be asked to carry their own weight in this battle. However, we could arrange a co-op arrangement for them if they use our device prominently in their marketing campaign. Is Ice Cream Sandwich strong enough to go head to head with iOS 5? I believe this type of campaign is long overdue.

Ice Cream Sandwich is a version of Google’s Android operating system. A Google spokesman declined to comment.

Dale Sohn, who headed Samsung’s U.S. mobile division until returning to Seoul as an executive advisor for the Korean giant, replied that it needed to “take advantage of this chance.”

Pennington replied with more thoughts on the matter.

Looking deeper into iPhone 4S, it is clear Apple is not worried about us as a hardware competitor, which is where are focusing. They are continuing to focus on the USER EXPERIENCE, which ultimately puts Google in the center of the target. I only bring this up because I passionately believe we must do something now, with or invisibly behind Google, to establish our collective advantages in consumers’ minds.

Pennington noted that Siri, a voice-based digital assistant, is one of the main features of the iPhone 4S. This poses a threat to Google, he notes, because more iPhone users may turn to Siri for search results versus Google.

“My point is, Google must be as motivated as we should be at this point,” he wrote.

A Samsung spokesman said Pennington has left the company recently, but he declined to disclose details on exactly when he left the company or the nature of his departure.

A few months after this email exchange, Samsung launched a successful campaign with the slogan – “The Next Big Thing is Already Here – that lampooned the fanaticism of Apple fans who are unable to see the advantages of Samsung’s smartphones. The success of Samsung’s campaign prompted Phil Schiller, Apple’s head of marketing, to consider firing its long-time advertising agency.